Programmer Humor

As a networker, ipv6 is the future. I'm a fan of it, but I don't really talk about it anymore because there's no point.

I threw in the towel after an ISP messed up so badly that I just couldn't bother anymore.

At a previous job a client I was doing some work for got a new internet connection at a new site, the ISP ran brand new fiber for it. This wasn't a new building or anything, but the fiber was new. They allocated them a static IPv4 thing as usual, and I asked the tech about V6, and they said we would have to take it up with the planning team, so I did. I was involved in the email chain at the end of the sales process to coordinate the hookup. So I asked. After many emails back and forth, I was informed the connection was allocated.

They allocated one single IPv6 subnet directly off of their device. I couldn't even.

For those that don't understand, the firewall we had connected to the device is an ipv6 router. What normally happens, especially in DHCP customer connections, is that the router will use DHCP-PD to allocate a subnet for the router to use on the LAN, and automatically set up a route to say "reach this subnet we allocated for this router, via this router" kind of thing. I'm dramatically simplifying, but that's the gist. In DHCP-PD, the router will also have an IPv6 address on the ISP-facing link to facilitate the connection. In the case of the earlier story, they gave us an entire subnet to communicate between the ISP and the router, and didn't give us a subnet for the client systems inside the network.

I did ask about this and I can only describe their reply as "visible confusion".

I know many who will still be confused by this point are people who have not used IPv6; to explain further: the IP on your local (LAN) systems needs to be a public IP address, because the router no longer does network address translation when sending your data to the internet. So the IP on the router has no bearing on your computer having a connection to the internet over v6. If your local computer does not have a globally unique ipv6 address, you cannot use IPv6. There are ways around this, NAT66 exists but it's incredibly bad practice in most cases. The firewall I was working with didn't really support NAT66 (at least, at the time) and I wasn't really going to set that up.

ISPs are the reason I gave up on IPv6.

I'll add this other story to reinforce it. I'll keep it brief. A different ISP for a different company at a different site entirely. The client purchased a static IPv4 address, and I asked about IPv6, as you do. To preface, I know this company and used them for my own connection at the time. They have IPv6 for residential clients via DHCP-PD. I was told, no joke, that because of the static IPv4 assignment, and how they execute that for businesses, that they couldn't add IPv6 to the connection, at all.

The last thing I want to mention is a video I saw, which is aptly named "CGN, a driver for IPv6 adoption" or something similar. It's a short lecture about the evils of carrier grade NAT, and how IPv6 actually fixes pretty much all the bs that goes with CGN, with fewer requirements and less overhead.

IPv6 is coming. You will prefer IPv4 until you understand how horrific CGN is.

But new IPv4 allocations have run out. I've seen ISPs that won the lottery in the 90s/2000s (when the various agencies controlling IP allocations just tossed them around like they were nothing) selling large blocks for big money.

Many ISPs offer only CGNAT, require signing up to the higher speed/more expensive packages to get a real IP, or charge extra on top of the standard package for one. I fully expect this trend to continue.

The non-move to IPv6 is laziness, incompetence, or the sheer fact they can monetize the finite resource of IPv4 addresses and pass the costs onto the consumer. I wonder which it is.

IPv4 dried up a long time ago. But it's different for every country. Countries like US and UK simply took over large blocks of IPv4 addresses and countries like Brazil got fucked. So, if you're in a country with a large pool, you won't notice any issues today, but if you're not so lucky, a lot of internet services are not accessible to you because some dickhead got IP banned and that IP is shared by thousands if not millions of users in your country.

The adoption of IPv6 on some segments of the Internet has lessened the crisis around IPv4 availability.

Honestly this isn't even true anymore. Most major ISPs have implemented dual stack now. The customer doesn't know or care because it's done at the CPE for them.

I use a browser extension which tells me if the site I'm at is 6 or 4 or mixed. In 2024 most major sites support V6. A lot of this is due to CDN supporting it natively.

The fact that GitHub doesn't is quickly becoming the exception.

If IPv6 is done right you don't even know you have it. If you use a cell phone or a home Internet, there is a high chance you are already using IPv6.

I've tried multiple times to go IP6 only. I mostly thought, despite my reasonable understanding of IP4, that I was the problem in trying to set it up. I found my dns host was being forgotten multiple times a day, set to something invalid, then it would time out and revert back to the working one. I couldn't figure out how to connect two computers together for Minecraft.

Now I hear it was just garbage consumer hardware and software? Fuck me. So much wasted time and effort to say nothing of believing I had turned into a tech idiot.

That is not the case for every country though. In France and Germany for example almost 3/4 of google requests are via IPv6.

What's “here”? Here in Germany, mine has it for maybe 10 years or so. Basically since launch day.

And new ISPs only have v6 since all legacy (v4) blocks have been sold years ago.

Because people in countries with ISPs that are unable to provide IPv4 (e.g. too expensive) can't access GitHub easily.

even easier then fingerprinting.

than*

Mine provides a connection, but doesn’t expose ports on v6. So I can access v6 services but can’t self-host any.

Roses in summer, violets in spring, it’s trivially easy this rhyming thing

IPv4 isn't depreciated, it's exhausted. It's still a key cornerstone of our current internet today.

We still have "modern" hardware being deployed with piss-poor IPv6 support (if any at all). Until that gets fixed, adoption rates will continue to be low. Adding warnings will only result in annoying people, not driving for improvement.

You shouldn't need to remember IP addresses, they invented DNS to solve that problem lol

Even so, the addresses can be even easier to remember because we get a-f as well as digits, my unique local subnet is fd13:dead:beef:1::/60 cause I like burgers haha

Assign a DNS name

Ok. So a device didn't get a dhcp address? No problem... It creates it's open IP address and starts talking and try to get out on internet on its own....

Its not that different from a conceptual point of view. Your router is still the gate keeper.

Home router to ISP will usually use DHCPv6 to get a prefix. Sizes vary by ISP but its usually like a /64. This is done with Prefix Delegation.

Client to Home Router will use either SLACC, DHCPv6, or both.

SLACC uses ICMPv6 where the client asks for the prefix (Router Solicitation) and the router advertises the prefix (Router Advertisement) and the client picks an address in it. There is some duplication protection for clients picking the same IP, but its nothing you have to configure. Conceptually its not that different from DHCP Request/Offer. The clients cannot just get to the internet on their own.

SLACC doesn't support sending stuff like DNS servers. So DHCPv6 may still be used to get that information, but not an assigned IP.

Just DHCPv6 can also be used, but SLACC has the feature of being stateless. No leases or anything.

The only other nuance worth calling out is interfaces will pick a link local address so it can talk to the devices its directly connected to over layer 3 instead of just layer 2. This is no different than configuring 169.254.1.10/31 on one side and 169.254.1.11/31 on the other. These are not routed, its just for two connected devices to send packets to each other. This with Neighbor Discovery fills the role of ARP.

There is a whole bunch more to IPv6, but for a typical home network these analogies pretty much cover what you'd use.